Well if you still have a local Radio Shack that hasn't done the disappearing brick & mortar blues, you might check there. They had different sized proto-boards.
Sparkfun has a few small boards:
Adafruit has their perma-proto boards:
While it is a breadboard, and not a perf-board where you solder things in, you can find these mini-breadboards in a lot of places:
http://www.dipmicro.com/store/SYB-170-WHITEIf you are going to cut the boards, you might go with these (note, I ordered some, and mine had a strong epoxy smell, so you might need to leave time for them to air out):
http://www.dipmicro.com/store/PCB-UNI7-GRN.
Here is another one for cutting. I haven't used this board, but I have ordered various things from the seller:
http://www.ebay.com/itm/10pcs-DIY-Prototype-Paper-PCB-Universal-Experiment-Matrix-Circuit-Board-5-x-7cm-/231349894869. They also sell the mini-breadboards.
All of these sellers ship fairly quickly. Sparkfun/Adafruit tend to ship in 1-2 days. Unfortunately, since Adafruit doesn't ship via US post office any more, it makes it more expensive when you are doing small orders, unless you can find a reseller (like pololu.com) that still has cheap mail options. Dipmicro is in Canada, but they have a courier that mails from the US 3 times a week. The NY Platform ebay seller generally mails out the next day.
There is the digispark prototype shield that you can get:
http://digistump.com/products/2. I have a Micro Center store near by, and they carry some digispark goodies. If you have a store near by, you might be able to pick it up locally.
